[PATCH] ia64: fix register-backing store initialization for main thread

arch/ia64/mm/init.c

@@ -121,7 +121,7 @@ ia64_init_addr_space (void)
 	vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
 	if (vma) {
 		vma->vm_mm = current->mm;
-		vma->vm_start = current->thread.rbs_bot;
+		vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
 		vma->vm_end = vma->vm_start + PAGE_SIZE;
 		vma->vm_page_prot = protection_map[VM_DATA_DEFAULT_FLAGS & 0x7];
 		vma->vm_flags = VM_READ|VM_WRITE|VM_MAYREAD|VM_MAYWRITE|VM_GROWSUP;